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BQ76952: Values CP1 and Resistor

Alan Montt
Prodigy 70 points
Part Number: BQ76952

Hi,

I've been determining some values for using 16 FET on BQ76952 considering MOSFETs with Ciss = 9250pF - 12000pF and Vbat = 32.4V, would it be ok to use CCP1=2.2uF 5%? would it be dangerous because it is in the limit? 
My second question is about the shunt resistors for measuring current with SRP and SRN, I'm dealing with 100A, is there any criteria or rule to determine what would be the value for the shunt resistor or how many resistors in parallel should I connect?

  • +1
    TI__Mastermind 25605 points

    Hi Alan,

    CCP1 = 2.2uF should be fine.

    There are a few things to consider with the current sense resistor. First is that the ADC has a measurement range of +/-200mV across the sense resistor. Any currents that generate a voltage outside this range won't be properly measured. Next is the power the sense resistor draws (P = I*V = I*I*R).

    We generally recommend a 1mOhm sense resistance. At 100A, this would equate to a 100mV drop across the resistor leaving plenty of room for any transients/short circuits to be properly measured. This would also mean that you need to choose resistors that can handle the total of 10W (10W = 100A * 100A * 0.001Ohm).

    Regards,

    Max Verboncoeur

  • 0 in reply to Max Verboncoeur
    Prodigy 70 points

    Thank you so much